Won't start-replaced key&tumbler,ignition switch, what now?fine 2days ago!

sounds like an ignition switch problem sometimes key is making contact to start and not other times

Most all vehicles have main power cable to starter solenoid which is mounted on the starter where the power cable to the switch connects OR there is a separate heavy gauge red wire connected to the positive post of the battery that leads to the ignition switch. Also check your ground cable by connecting battery jumper cable to negative post on battery and other end to metal frame of van.

When it will not crank, a mechanic would check for voltage at the starter, the clutch safety switch, and the key switch.

Your ignition switch may be defective. try to borrow a remote starter to see if it will crank without using your ignition switch

It won't die when pulling the relay because it has another power path to the fuel pump through the oil pressure switch . Fuel Pump Electrical Circuits Description and Operation watch this video on fuel pump control , shows chrysler first , ford ,then gm . wait for gm an he explains the oil pressure switch . Plus when it won't start ,don't guess or theorize ! Test what's missing ? check for spark , no spark check ignition system , coil's , ignition module , crank sensor etc... has spark ,do a fuel pressure test etc... don't think computer , when it won't start does the check engine light come on with the key on run not start . If light is lit ,nothing wrong with the cumputer . If want to fix cars you really should take some automotive classes . Test don't guess .Watch some other videos crank no start videos etc...

Start with the simple and check the fuse to the ECM. It may have blown and the crank shaft sensor wire harness which is located on the passenger side of the harmonic balance. The other thing also would be a problem with the passlock system if the van is equipped with one. Try turning the ignition key to the on position for 10 min then try starting the engine. Good luck and hope this helps.

most likely its the ignition cylnder (tumbler)

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Not an exact solution, but perhaps information that might lead to one.

1.Replaced the tumblers? I believe I would replace the entire ignition switch this time. It's my belief that the body of the ignition switch is worn inside, and will keep damaging the tumblers.

2.Do you have a tilt steering wheel? It's best to keep the steering column in straight line when starting the car, then tilt the wheel to where you want, after the car is started. When the steering column is in a tilted position, it puts undue strain on the ignition key switch, and the mechanism the ignition key switch operates, on GM vehicles.

This mechanism, consists of a half moon gear on the ignition key switch, that turns inside a 'Planetary' gear. I used the term 'Planetary', as the gear shape is hard to describe. It resembles an oblong loop, shaped like the number 9, with gear teeth on the inside bottom of the loop. This 'Loop' rotates, when the gear teeth of the ignition key switch, engage the teeth on the loop, and pushes a rod, or retracts the rod. The rod goes down the side of your steering column, and turns on, or turns off an ignition switch, located at the bottom left side of the steering column.

Having the steering wheel tilted, puts a strain on the ignition key switch internals, the oblong loop can break, and/or gear teeth can be stripped off.

shifter cable has moved from correct position.

It definitely sounds like the electrical part of your ignition isn't working properly.When you turn the key, the lck and tumbler turns on the ign. switch in which sends power to the rest of the car.